Node.js Buffer.readUInt32BE()用法及代碼示例

Buffer.readUInt32BE()方法是Buffer模塊中Buffer類的內置應用程序編程接口，用於從指定的緩衝區讀取指定偏移量的32位值。

用法:

Buffer.readUInt32BE( offset )

參數：此方法接受單個參數偏移量，該偏移量指定在讀取之前要跳過的字節數，或僅表示緩衝區中的索引。 offset的值為0

返回值：此方法以Big Endian格式返回從緩衝區讀取的整數值。

以下示例說明了Node.js中Buffer.readUInt32BE()方法的使用：

範例1：

// Node program to demonstrate the   
// Buffer.readUInt32LE() Method 
   
// Allocating buffer from array 
const buf = Buffer.from([0x21, 0x09, 0x19, 0x98, 
                    0x16, 0x09, 0x19, 0x96]); 
  
// Printing allocated buffer 
console.log(buf); 
   
// Reading 32 bits data from the buffer 
// and printing it as a string 
console.log(buf.readUInt32BE(0).toString(16)); 
console.log(buf.readUInt32BE(1).toString(16)); 
console.log(buf.readUInt32BE(2).toString(16)); 
console.log(buf.readUInt32BE(3).toString(16)); 
console.log(buf.readUInt32BE(4).toString(16));

輸出：

<Buffer 21 09 19 98 16 09 19 96>
21091998
9199816
19981609
98160919
16091996

範例2：

// Node program to demonstrate the   
// Buffer.readUInt32LE() Method 
   
// Allocating buffer from array 
const buf = Buffer.from([0x21, 0x09, 0x19, 0x98, 
                    0x34, 0xae, 0xe8, 0xff]); 
  
// Printing allocated buffer 
console.log(buf); 
   
// Reading 16bits data from the 
// buffer and printing it as a string 
console.log(buf.readUInt32BE(0).toString(16)); 
console.log(buf.readUInt32LE(0).toString(16)); 
console.log(buf.readUInt32BE(1).toString(16)); 
console.log(buf.readUInt32LE(1).toString(16)); 
console.log(buf.readUInt32BE(2).toString(16)); 
console.log(buf.readUInt32LE(2).toString(16)); 
console.log(buf.readUInt32BE(3).toString(16)); 
console.log(buf.readUInt32LE(3).toString(16)); 
console.log(buf.readUInt32BE(4).toString(16)); 
console.log(buf.readUInt32LE(4).toString(16));

輸出：

<Buffer 21 09 19 98 34 ae e8 ff>
21091998
98190921
9199834
34981909
199834ae
ae349819
9834aee8
e8ae3498
34aee8ff
ffe8ae34

範例3：

// Node program to demonstrate the   
// Buffer.readUInt32LE() Method 
   
// Allocating buffer from array 
const buf = Buffer.from([0x21, 0x09, 0x19, 0x98]); 
  
// Printing allocated buffer 
console.log(buf); 
   
// Reading 16bits data from the buffer 
// and printing it as a string 
console.log(buf.readUInt32BE(0).toString(16)); 
   
// Wrong index is provoded to produce error 
console.log(buf.readUInt32BE(1).toString(16));

輸出：

<Buffer 21 09 19 98>
21091998
internal/buffer.js:49
  throw new ERR_OUT_OF_RANGE(type || 'offset',
  ^

RangeError [ERR_OUT_OF_RANGE]:The value of "offset" is out of range.
It must be >= 0 and <= 0. Received 1
    at boundsError (internal/buffer.js:49:9)
    at Buffer.readUInt32BE (internal/buffer.js:192:5)
    . . .

注意：上麵的程序將通過使用node index.js命令。

參考： https://nodejs.org/api/buffer.html#buffer_buf_readuint32be_offset

相關用法

注：本文由純淨天空篩選整理自anwesha0107大神的英文原創作品 Node.js | Buffer.readUInt32BE() Method。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。